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Learn how to effectively convert SQL queries to Lambda LINQ expressions with `inner join` on multiple conditions in C-.
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Converting SQL to Lambda LINQ: Handling Inner Joins with Multiple Conditions

Working with SQL often brings forth various complexities, especially when you're translating those queries into LINQ expressions in C-. One common scenario is needing to implement an INNER JOIN with multiple conditions, which can be particularly challenging. This guide will guide you through converting a complex SQL query into a LINQ expression, ensuring that you handle those multiple conditions effectively.

Understanding the SQL Query

Let's start by analyzing the SQL query you provided. Here's the SQL command we need to convert:

[[See Video to Reveal this Text or Code Snippet]]

Breakdown of the SQL Query

Selected Columns: The query retrieves specific columns from both LotProgress and MaterialMount tables.

Inner Join:

The join condition checks for equality in MachineNo.

It also checks if the ParentMachineNo from the Machine table matches.

Time Constraints: The query further filters the results based on the StartTime and EndTime, allowing for cases where EndTime can be NULL.

Converting SQL to Lambda LINQ Expression

Now that we have a clear understanding of the SQL query, let’s move on to how we can achieve this using Lambda LINQ expressions.

Step-by-Step Conversion Guide

Start with the LINQ Join: The first portion of the query transforms into a LINQ Join.

Add Conditions for Joining: Utilize conditional Where statements to handle your multiple conditions.

Select Results: Map your results into a new anonymous type or a custom class.

Here’s how it looks in LINQ:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the LINQ Code

Join Statement: This connects LotProgress to MaterialMount based on MachineNo.

Where Conditions:

The first condition checks both the MachineNo and the ParentMachineNo from the Machine table.

The next two Where clauses ensure that time overlaps are correctly processed and allow for nullable EndTime.

Select Statement: Finally, it constructs a new anonymous type with the desired properties.

Conclusion

Converting SQL queries to LINQ can seem daunting, especially when you have to cater to multiple joining conditions. However, with a structured approach, using joins and filtering conditions can help you achieve the same results effectively.

This guide hopefully clarifies the process and provides you with the necessary tools to handle complex SQL to LINQ conversions in your projects. Remember, taking the time to understand the query structure will make translation much smoother!

Feel free to share your comments or questions below, and happy coding!